The San Miguel plate. Relief from Copernicus GLO-30; rivers and lakes from USGS NHD; watersheds from the USGS Watershed Boundary Dataset; roads and city limits from Census TIGER 2024.
San Miguel’s center stands about 2,470 ft above sea level. Within three miles the land runs from 2,410 ft to 2,640 ft, a difference of 230 ft: rolling country. The highest named summit within 15 miles is La Jolla Peak, about 6,110 ft, 15 miles northeast.
Under the town center the state geologic map shows Quaternary surficial deposits, undivided (sand, silt, clay), from the Pleistocene to Holocene, less than 2 million years old.
The section below crosses 4 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 9×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Sand, silt, clay. Age: Pleistocene to Holocene, less than 2 million years old. About 9 mi of the line.
Sandstone, siltstone, conglomerate. Age: Middle Jurassic to Late Jurassic, 150 to 170 million years old. About 5 mi of the line.
Gravel, sand. Age: Late Pliocene to Pleistocene, 0.8 to 3 million years old. About 2 mi of the line.
Diorite, alkali-granite, granodiorite. Age: Early Jurassic to Late Jurassic, 150 to 180 million years old. About 0.8 mi of the line.
From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale.
Heights from Copernicus GLO-90 (a surface model: it includes buildings and tree canopy); summits from USGS GNIS; rivers from USGS NHDPlus HR; rock from the USGS State Geologic Map Compilation.